Abstract
Introduction: The nutrient requirements for culturing human pluripotent stem cells (hPSCs) have been studied in relation to the development of chemically defined media. Most hPSC media contain FGF2, which is critical for hPSC growth and maintenance. Here, we investigated compounds that could substitute for FGF2 activity. Methods: To identify compounds that can replace FGF2 and promote the proliferation of undifferentiated hPSCs, we screened our compound library using the hOCT4-EGFP reporter system and evaluated candidates using cell morphological analysis and OCT4 immunostaining as a marker of undifferentiated cells. We further evaluated the extent to which the selected compound can replace FGF2 through long-term culture (over 10 passages). We examined whether the compounds promote the reprogramming efficiency of somatic cells into induced pluripotent stem cells (iPSCs) using mRNA reprogramming. We also analyzed which signaling pathways were activated by the compound using western blotting. Results: We identified a new compound, NN15-017, which enables a reduced concentration of FGF2 in the medium by 5-fold and enhances the reprogramming efficiency of human induced PSCs by 2- to 3-fold. NN15-017 promoted the MAP/ERK signaling pathway downstream of FGF2 and may affect the Hippo-YAP signaling pathway in hPSCs. Conclusions: NN15-017 reduces the requirement for FGF2, thereby providing novel and valuable benefits for the proliferation and generation of human induced PSCs.